A conventional moire deflectogram produced by light reflected from the anterior surface of the cornea is sensitive to both the radius of curvature of the anterior cornea surface and the distance of a compensating lens form the anterior surface of the cornea. In such systems, it is necessary to make an independent measurement of the position of the compensating lens in order to evaluate the radius of curvature of the cornea. In accordance with the keratometer set forth in the above-referenced parent application, two probe light beams are used to make two independent deflectogram measurements of the cornea. As a result of the invention therein, the position of the compensating lens and the radius of curvature of the anterior surface of the cornea can be determined simultaneously without independent measurement.
Because the above-referenced parent application sets forth a single system geometry, and because additional geometries may be found beneficial in certain environments, there remains a need in the art for additional systems for keratometry which remain translation insensitive.